To determine whether early exposure to lesser doses of lead is accompanied by long term neurocognitive effects, we will follow up at least 102 of the children whom we intensively studied in 1976-1977. At that time we evaluated their neuropsychological function in relation to their dentine lead levels. The children, now 17-18 years of age, will be restudied with respect to their psychometric intelligence, attention, perceptual function, need for special school services, and disciplinary actions. The correlation between deficit demonstrated in 1979 and contemporary dysfunction will be evaluated. Psychosocial factors which are associated with greater or lesser risk for deficit will be identified. From the need for special services, school function, and opportunity cost for the parents, health production functions will be estimated to monetize the long term costs of early exposure to lead at low dose.